The present invention generally relates to communication systems, and, more particularly, to a communication system having physical interfaces and a communication controller, and to a method.
In many communication systems, a physical interface (xe2x80x9cPHYxe2x80x9d) connects a communication channel (e.g., fiber optic line, phone line, radio link) to a communication controller. Preferably, a single communication controller can serve multiple (e.g., N) interfaces. The controller regularly requests status information from the interfaces (polling).
For example, in a communication system operating in the Asynchronous Transfer Mode (ATM), the channels transfer data in cells (e.g., blocks of bytes). In the terms of ATM, controller, interfaces and channels belong to the so-called physical layer. Many references are dedicated to ATM, such as: [1] Reif O. Onvural: xe2x80x9cAsynchronous Transfer Mode, Performance Issuesxe2x80x9d, Second Edition, Artech House Boston and London, 1995, ISBN 0-89006-804-6, especially chapter 2.4 xe2x80x9cPhysical Layerxe2x80x9d; [2] The ATM Forum, Technical Committee: xe2x80x9cUtopia Level 2, Version 1.0xe2x80x9d, June 1995. FIG. 2.3B of [2] illustrates a single ATM (communication controller) and multiple PHYs; [3] U.S. Pat. No. 5,485,456 to Shtayer et al.; and [4] U.S. Pat. No. 5,418,786 to Loyer et al.
Controller and interfaces are often located in different integrated circuits in different packages which are electrically connected by pins, terminals, connectors, wires, or other devices. The number of such connections, hereinafter collectively xe2x80x9cpinsxe2x80x9d influences the total costs of the system and prevents using the full capacity of the controller. Therefore, it is desirable to reduce the pin number.
The present invention seeks to provide an improved communication system which mitigates or avoids these and other disadvantages and limitations of the prior art.